Erion is the Greek word for wool — the fleece of sheep or goats. It appears twice in the New Testament: Hebrews 9:19 describes Moses sprinkling blood and water with hyssop and scarlet wool (erion) at the covenant ceremony, and Revelation 1:14 describes the risen Christ: 'The hair of his head was white like wool [erion], white as snow.' The word carries both ritual purity imagery (Hebrews) and divine glory imagery (Revelation).
White wool (erion) becomes in Revelation 1:14 the color of eternal purity and divine authority. The white hair of the Ancient of Days (Dan 7:9) is recalled — Christ shares in the divine eternity and holiness. But the ritual use in Hebrews 9:19 is equally profound: the erion dipped in blood and hyssop water was the instrument of covenant-sealing, connecting with Isaiah 1:18 — 'though your sins are like scarlet, they shall be as white as wool.' The progression is complete: sin is scarlet, the sacrificial blood is applied with erion (wool), and the result is whiteness — the very whiteness of the glorified Christ.